Many conjectures have been advanced, and an endless discussion created, to account for the watering or “_jowher_” in oriental sword-blades, and genuine Damascus gun-barrels. Anything approaching the truth is seldom met with; though I think the explanation is very simple. It must be well known that there is an immense variety of different qualities in both iron and steel: no uniformity of quality is found in two productions out of a hundred. The very ore, the coal, the presence of oxygen, the excess of it, all vary the quality of the material. An excess of carbon is more detrimental than a scarcity; for where carbon has once been, it leaves an indelible mark, and though extracted to as great an extent as practicable, it leaves a residue that possesses an affinity to absorb carbon again equal to the original quantity: thus, steel once made will never, by any process yet known, be reconverted back to iron of the same nature it was originally. Mr. Mushet has given us the proportions of carbon _held in solution_ by the various qualities of steel and iron, and the reader will find them in the note below.[9] It inevitably follows, as a principle, that the quantity of carbon contained in the metal--avoiding cast iron--will increase or decrease, and thus regulate the degree of hardness of the metals in question. A quantity of metals dissimilar in this particular, mixed together, and run into a vessel in a state of fusion, then, when cold, filed and polished, will show a variety according to the place they hold in the crystallised mass. Work and twist this material in all the tortuous ways and shapes it is capable of, and you only twist the fibres of the different bodies in the same way; and when they come to be acted upon by acid or oxidisation, they still retain their relative positions, forming the watering or figure, as was the intention of the tortuous twisting. All the beautiful arrangements in Damascus figures are obtained in this way. Metals containing more or less carbon will always produce this watering. To obtain a satisfactory proof, any person may case-harden a few pounds weight of stubs, and afterwards melt them in a crucible, and run them into a receiver; when these are worked down into the bar (or not, as he pleases), dress and apply a little sulphuric acid, and the peculiar situation the various stubs had taken in the fluid state, will be clearly discernible.